Playing back audio recorded with AVCaptureAudioDataOutput

Question

Created Feb ’21

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I'm trying to record video and audio and sending them over the network so that they can be played back in real time on other clients. I've managed to record and play back video successfully, but audio still cannot be played back (see AVAudioPlayer at the bottom of the code below). What am I doing wrong or what is missing? Thank you in advance for any input.

Code Block swiftlet captureSession = AVCaptureSession()
private func startVideoAudioFeed() {
    let sessionPreset = AVCaptureSession.Preset.low
    if captureSession.canSetSessionPreset(sessionPreset) {
        captureSession.sessionPreset = sessionPreset
    }
    switch AVCaptureDevice.authorizationStatus(for: .video) {
    case .notDetermined:
        AVCaptureDevice.requestAccess(for: .video) { success in
            self.startVideoAudioFeed()
        }
    case .authorized:
        captureSession.beginConfiguration()
        let captureVideoDevice = AVCaptureDevice.default(.builtInWideAngleCamera, for: .video, position: .front)!
        let captureVideoInput = try! AVCaptureDeviceInput(device: captureVideoDevice)
        if captureSession.canAddInput(captureVideoInput) {
            captureSession.addInput(captureVideoInput)
        }
        let captureVideoOutput = AVCaptureVideoDataOutput()
        captureVideoOutput.setSampleBufferDelegate(self, queue: DispatchQueue.main)
        if captureSession.canAddOutput(captureVideoOutput) {
            captureSession.addOutput(captureVideoOutput)
        }
        captureSession.commitConfiguration()
        captureSession.startRunning()
    default:
        break
    }
    switch AVCaptureDevice.authorizationStatus(for: .audio) {
    case .notDetermined:
        AVCaptureDevice.requestAccess(for: .audio) { success in
            self.startVideoAudioFeed()
        }
    case .authorized:
        captureSession.beginConfiguration()
        let captureAudioDevice = AVCaptureDevice.default(for: .audio)!
        let captureAudioInput = try! AVCaptureDeviceInput(device: captureAudioDevice)
        if captureSession.canAddInput(captureAudioInput) {
            captureSession.addInput(captureAudioInput)
        }
        let captureAudioOutput = AVCaptureAudioDataOutput()
        captureAudioOutput.audioSettings = [AVFormatIDKey: kAudioFormatLinearPCM, AVNumberOfChannelsKey: NSNumber(value: 1), AVSampleRateKey: NSNumber(value: 44100)]
        captureAudioOutput.setSampleBufferDelegate(self, queue: DispatchQueue.main)
        if captureSession.canAddOutput(captureAudioOutput) {
            captureSession.addOutput(captureAudioOutput)
        }
        captureSession.commitConfiguration()
    default:
        break
    }
}
func captureOutput(_ output: AVCaptureOutput, didOutput sampleBuffer: CMSampleBuffer, from connection: AVCaptureConnection) {
    if let imageBuffer = sampleBuffer.imageBuffer {
        let ciImage = CIImage(cvPixelBuffer: imageBuffer)
        let cgImage = CIContext().createCGImage(ciImage, from: ciImage.extent)!
        let data = CFDataCreateMutable(nil, 0)!
        let imageDestination = CGImageDestinationCreateWithData(data, kUTTypeJPEG, 1, nil)!
        CGImageDestinationAddImage(imageDestination, cgImage, [kCGImageDestinationLossyCompressionQuality: NSNumber(value: 0)] as CFDictionary)
        CGImageDestinationFinalize(imageDestination)
        play(data: data as Data)
    } else if let dataBuffer = sampleBuffer.dataBuffer {
        let data = try! dataBuffer.dataBytes()
        play(data: data)
    }
}
private func play(data: Data) {
    if let image = CGImage(jpegDataProviderSource: CGDataProvider(data: data as CFData)!, decode: nil, shouldInterpolate: false, intent: .defaultIntent) {
        // image is a valid image
    } else if let audioPlayer = try? AVAudioPlayer(data: data) {
        audioPlayer.play()
        // audioPlayer is always nil with error: Error Domain=NSOSStatusErrorDomain Code=1954115647 "(null)"
    }
}

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